A major topic of developing a novel electrolytic capacitor is increasing the conductivity and stability of the electrolyte to reduce the equivalent series resistance (ESR) and improve the reliability of a capacitor. A conductive conjugated polymer has higher conductivity and stability than a liquid-state electrolyte or a solid-state organic semiconductor complex salt (e.g. TCNQ composite salt) in a conventional electrolytic capacitor. As a result, the conductive conjugated polymer is one of the best candidates for the electrolyte of the electrolytic capacitors with low ESR and high reliability.
Although a conductive conjugated polymer used as the electrolyte of an electrolytic capacitor has the advantages mentioned above, however, the withstanding voltage of the capacitor with a conductive conjugated polymer is dramatically lower than that of the capacitor with a liquid-state electrolyte. In addition, the permeability of the conductive conjugated polymer in the micro-hole of the dielectric layer is dramatically lower than that of the liquid-state electrolyte. As such, the low working voltage and low capacitance are the major shortcomings for the electrolytic capacitor with a conductive conjugated polymer served as an electrolyte.
Accordingly, a novel conductive composite for electrolyte is called for to overcome the limitations described above to enhance the performance of the electrolytic capacitor.